Gary Illyes @goog said this was happening Q1 this year, and like others mentioned lots of other direct/indirect signals have pointed this way.

http://searchengineland.com/google-may-discontinue-ajax-craw... March 5th: Gary said you may see a blog post at the Google Webmaster Blog as soon as next week announcing the decommissioning of these guidelines.

Pure speculation but interesting... The timing may have something to do with Wix, a Google Domains partner, who is having difficulty with their customer sites being indexed. The support thread shows a lot of talk around "we are following Google's Ajax guidelines so this must be a problem with Google". John Mueller is active in that thread so it's not out of the realm of possibility someone was asked to make a stronger public statement. http://searchengineland.com/google-working-on-fixing-problem...